Electric motors for driving loads of the type for which the present invention is targeted, heretofore involved the use of extensive transmission gearing to augment the electrically generated drive forces. Such motor drive systems also had brake/clutch arrangements associated therewith for load safety purposes under power-off conditions. Hydraulic systems were also utilized for converting the electrical generated energy into heavy load lift forces, and involved extensive maintenance to avoid fluid leakage and associated hazards as well as to require additional fail safe brakes.
Although magnetostrictive motor systems involving use of roller locking arrangements are already known, they have not been adapted to or suitable for use in the drive of the aforementioned loads to which the present invention is targeted. Such magnetostrictive motor systems are disclosed for example in various patents involving the inventors of the present invention as inventor or co-inventors. Such patents consist of: U.S. Pat No. 5,039,894 issued Aug. 19, 1991; U.S. Pat. No. 5,041,753 issued Aug. 20, 1991; U.S. Pat. No. 5,079,460 issued Jan. 7, 1992, U.S. Pat. No. 5,482,144 issued Jan. 9, 1996; U.S. Pat. No. 5,530,312 issued Jun. 25, 1996; and U.S. Pat. No. 5,705,863 issued Jan. 6, 1998.
It is an important object of the present invention to provide magnetostrictive motor systems generating sufficiently high drive forces for transfer to certain targeted loads in an efficient and reliable manner, involving relatively simple and less costly arrangements for imparting either linear or rotary motion to the driven load.
In accordance with the present invention, an electric motor unit for either linear or rotary motion applications, is provided with a magnetostrictive locking arrangement through which cyclically generated driving force is transferred to a load under directional switching control of a Lorentz force type of magnetic field unlocking system. The magnetostrictive locking arrangement involves sprag locking by multi-dimensional rollers that are spring loaded to provide motor lock up during electric power-off conditions so as to act as a brake. Such rollers undergo controlled engagement for transfer of high drive forces cyclically generated by magnetostrictive expansion of actuators, to reliably impart either linear or rotary motion directly to a load in a selected direction through a relatively simple force transfer arrangement which accommodates direction switching under load.